Field of the Invention
The invention relates generally to bone spacers utilizing a helical lock and specialized surgical instruments and methods for insertion thereof.
Description of Related Art
The prior art illustrates a variety of approaches to secure a spacer between two bone segments. These bone segments are typically vertebral bodies and the spacer is typically an intervertebral spacer. Crozet for example (US 2002/0177898) discloses a spacer and screw like members having a helical thread that engages the surface of the bone to fix the spacer in position. Landry (US2014/0114418) uses a similar open helical device to accomplish a similar feat to cause fixation of a facet joint. Carlson (U.S. Pat. No. 8,900,310) also combines a rotating helical member within a spacer as does Laurence (US 2011/0166660) who uses an open helix device and discloses an open helix insertion tool. McKenny (US2014/0052260) discloses an spacer design utilizing a first curved path blade that is inserted through an aperture of the spacer. Mujwid (U.S. Pat. No. 7,297,162) discloses an expandable spring like implant that bulges upon compression of the spring. Lieberman (U.S. Pat. No. 6,689,168) discloses an open helix device for advancing into a pair of adjacent vertebral bodies. Bolduc (U.S. Pat. No. 6,296,656) discloses an array of open helix designs and an applicator device for insertion.
A need remains for robust intervertebral spacers that are inserted using a minimally invasive approach requiring only a minimal incision to gain access to the intervertebral space along a single surgical axis. In addition, a need remains for spacers that include a fixation mechanism that not only holds the spacer in a pre-determined position between bone portions but also secures a bone portion, or an endplate in the case of a vertebral body, to the entire length of the corresponding face of the spacer without liftoff or gapping therebetween with skeletal movement. A need remains for spacer fixation systems that can be applied along a single surgical axis and do not require off angle insertion or tightening of fixation components. A need remains for spacer fixation systems that may be easily removed and adjusted once implanted if the need arises. A need remains for spacer and spacer fixation systems that can be inserted and deployed without a continual insertion and removal of multiple instruments. A need remains for spacer fixation systems which have a minimal profile to minimize disruption of the bone endplate and don't require pre-drilling. A need remains for spacer insertion instruments that simultaneously control both the spacer and the spacer fixation providing precise placement of not only the spacer but also simultaneous placement of the spacer fixator.